A. Hexagonal-rhombohedral crystal system--uniaxial (see Crystal System handout)

1. Characteristics (same as beryl).
2. Doubly refractive (same as beryl).

B. Chemical Composition

1. Chemical group = aluminum oxide

2. Pure corundum is colorless. Trace elements cause different colors.

a. red = chromium (Cr)

b. blue, green = titanium, iron oxide (Ti, Fe)

c. orange = Cr, Fe

d. purple = Cr, Fe, Ti

3. All varieties have the same chemical and physicalcharacteristics, differing only in the kind and amount of trace elements

a. Ruby is medium light to dark tone with orangy-red to purple-red color

b. Sapphire used alone is the blue variety and is greenish-blue to violety-blue

c. Fancy sapphires--all varieties of corundum except red and blue (pink, yellow, green, purple)

d. Phenomenal varieties

1) star ruby

2) star sapphire

C. Trade Names--historically referred to source area. Today--quality of gemstones.

1. Burma, Burmese ruby--finest color of medium dark red to purplish-red (pig'eon's blood) color

2. Ceylon, Sri Lanka ruby--lighter tone, very brilliant (luster)

3. Thai, Siam ruby--dark tone, red to bluish-red to purplish-red color (may resemble garnet)

4. African ruby--orange-red color

5. Kashmir sapphire--finest color of medium to medium dark tone, slightly violety-blue (cornflower blue) color with a sleepy, velvety look due to inclusions

6. Burma sapphire--medium to medium dark tone, slightly violetyblue color

7. Thai, Siam sapphire--dark blue color

8. Ceylon, Sri Lanka--lighter tone, very brilliant, grayish blue to violety-blue color

9. Montana sapphire--light tone, very brilliant, ^"steely^" appearance

10. Australian sapphire--very dark and inky

11. Padparadscha sapphire--light to medium tone, pinkish-orange to orangy-pink color

D. Source Areas

1. Most common formation in contact metamorphosed limestone (limestone has the necessary trace elements and aluminum oxides)

2. Ruby--Mogok, Burma (finest), Sri, Lanka, Cambodia, Thailand, East Africa

3. Sapphire--same as rubies, plus Australia, Montana, and Kashmir, India (finest)

E. Gem Lore

1. Ruby

a. Name from Latin ¹¹ruber¹¹, meaning red

b. Symbol of passion, exuberance, vitality

c. July birthstone (summer vitali~y)

d. Medicinal--immunity from the sword, spear, or gun when inserted under skin

2. Sapphire

a. Sapphire historically also used to denote lapis lazuli and other opaque blue minerals

b. Symbol of truth, faithfulnes~, and sincerity

1) protected against harm and envy

2) believed to stop shining when worn by wicked

c. Medicinal

1) power to free from poisons and demons

2) removes impurities and foreign matter from eyes

3. Star Sapphire

a. Stone of destiny

b. Three rays of star (chatoyant bands) symbolize faith, hope and charity

4. Hindus, Burmese, and Sri Lankans historically believed

a. Colorless sapphire was an unripe ruby

b. Pale rubies, if buried, would darken

c. Flawed stones were overripe

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